Combustion Engineering

替代燃料的开发和实施目前对航空工业具有重大意义。随着对传统燃料排放的环境影响的关注增加，对使用更新、创新、清洁燃料的需求也在增加。基于石油资源的传统燃料的可获得性和成本的不确定性也是推动新燃料开发的一个因素。合成生产的燃料可以通过各种方法和来源获得。这些燃料在成分和性质上与传统喷气燃料相似。这使得喷气燃料的成分可以通过整合合成燃料和使用航空混合燃料来增加。虽然以前已经考虑了许多这些燃料的排放，但在考虑影响发动机性能和寿命的其他重要因素时，存在显着的知识差距。该项目将试图通过生成一个整体模型来填补这一空白，该模型将试图将整个发动机对一系列替代燃料的反应进行分类。该项目将设法调查使用不同替代燃料混合物的各种燃烧系统的性能。这将包括分析对以下方面的影响：i）燃烧室和发动机噪音ii）燃烧室和发动机振动iii）燃烧不稳定性iv）发动机寿命v）颗粒排放的大小和密度vi）热信号该项目将包括四个阶段：i）燃料选择将选择一系列替代燃料、混合物和替代物。这将涉及对目前所有可用的替代燃料、代用品和混合物进行系统审查。所研究的燃烧特性主要取决于有关燃料的沸点、粘度、蒸汽压、密度、单位体积能量密度、单位质量能量密度、火焰速度和十六烷值。因此，所选燃料的范围将需要各种性能特征来满足这些标准。将对每种选定的燃料进行气相色谱分析，以确定其化学成分。ii）实验阶段1选定的燃料将在一系列当量比下燃烧，以研究每种燃料对先前列出的标准的影响。大多数低排放技术燃烧燃料，其中与空气相比燃料的比例较低，也称为稀燃。因此，将特别强调在稀燃比下对燃料进行试验，以便有效地评估每种替代燃料，因为这些结果将具有最大的相关性。在这一阶段将使用两种不同尺寸的燃烧室，以研究和分析不同尺寸燃烧室的不稳定性，这两种尺寸都可在LCCC获得。iii）试验阶段2A小型燃气涡轮机发动机或APU将使用与阶段1相似的方法选择的燃料。然而，在这一阶段，还将燃烧基准燃料，以提供性能方面的比较。由于燃气涡轮机引入了独立燃烧室中没有的更高的压力比，因此在该平台上进行的测试将使用与实际发动机更相关的配置来提供性能不稳定性数据。iv）数据分析和建模将对实验数据进行分析，以便生成替代燃料对各种因素的影响的整体模型，这些因素例如振动、噪声、排放、热特征、燃烧不稳定性，颗粒的大小和密度，并将允许预测发动机寿命和任何潜在的维护。将对该模型进行测试，方法是对实验阶段未包括的现有燃料进行预测，测试这些燃料，然后将模型预测与实验数据进行比较。

The development and implementation of alternative fuels is currently of significant interest to the aviation industry. As the concern over the environmental impact of the emissions of traditional fuel increases, so does the demand for newer, innovative, cleaner fuels to be used. The uncertainty as to the availability and cost of traditional fuel based on oil resources is also a factor driving the development of new fuels. Synthetically produced fuels can be obtained via various methods and sources. These fuels are similar in composition and properties to those of traditional jet fuel. This allows the composition of jet fuel to be augmented by integrating synthetic fuel and using the blended fuel for aviation.While the emissions of many of these fuels have been considered previously, there is a significant knowledge gap when it comes to considering the other significant factors that affect an engines performance and lifespan. This project would seek to fill that gap by generating a holistic model that would seek to categorise the entire engine response to a range of alternative fuels. This project would seek to investigate the performance of a variety of combustion systems using different variations of alternative fuel blends. This would include analysing the effect on:i) Combustor and Engine Noise ii) Combustor and Engine Vibrationiii) Combustion Instabilityiv) Engine Lifev) Size and Density of Particulate Emissionsvi) Heat SignatureThis project would be comprised of four stages:i) Fuel SelectionA range of alternative fuels, blends and surrogates will be selected. This will involve a systematic review of all currently available alternative fuels, surrogates and blends. The combustion characteristics being studied are predominantly determined by the boiling point, viscosity, vapour pressure, density, energy density per volume, energy density per unit mass, flame speed and cetane rating of the fuel in question. For this reason, the range of fuels selected will need a variety of performance characteristics to fit these criteria. Gas chromatography analysis would be used on each fuel selected to determine its chemical composition.ii) Experimental Phase 1The fuels selected will be burned at a range of equivalence ratios to investigate the effect of each fuel on the criteria listed previously. A majority of low emission technologies burn fuel where there is a lower proportion of fuel compared to air, also known as a lean burn. For this reason, particular emphasis will be placed on experimenting with fuels at lean ratios in order to effectively evaluate each alternative fuel as these results will have the most relevance. Two different sizes of combustor will be used at this stage in order investigate and analyse the instabilities in different combustor sizes, both of which are available at the LCCC. iii) Experimental Phase 2A small gas turbine engine, or APU, will be used with the fuels selected with a similar methodology to Phase 1. During this phase however, baseline fuels will also be burnt in order to provide a comparison in terms of performance. As a gas turbine introduces higher pressure ratios not found in stand-alone combustors, testing on this platform will provide performance instability data using a configuration more relevant to actual engines.iv) Data Analysis and ModellingThe experimental data will be analysed in order to generate a holistic model of the effect of alternative fuels on a variety of factors, such as vibrations, noise, emissions, heat signature, combustion instability, the size and density of particulates and would allow predictions of the engine life and any potential maintenance. The model will be tested by making predictions on currently available fuels not included in the experimental phase, testing them and then comparing the models predictions to the experimental data.